1. Field of the Invention
The present invention relates to a polyamide solid phase having introduced onto the surface thereof a functional group capable of immobilizing a biochemical substance, and to a polyamide solid phase having immobilized thereto a biochemical substance.
2. Description of the Related Art
In recent years, techniques for effectively analyzing gene functions of various organisms have rapidly advanced. In order to analyze base sequence of DNA or DNA fragment to be used in the techniques, a detecting tool, called DNA chip, has been used which comprises a solid phase substrate having immobilized on the surface thereof many nucleotide derivatives such as DNA's, DNA fragments or synthetic oligonucleotides as detecting molecules. Such detecting molecules bound and immobilized onto the solid phase substrate are also called probe molecules. A typical DNA chip is a microarray comprising a solid-phase carrier such as a glass plate having many probe molecules arrayed and immobilized thereon.
The DNA chip has made it possible to effectively examine expression, variation and polymorphism of a gene in a short time. Preparation of the DNA chip, however, requires a technology for arraying many DNA fragments or oligonucleotides with a high density and a high stability on the surface of the solid-phase substrate.
In the case where the probe molecule to be immobilized is a synthetic oilgonucleotide, there has been known a technique of immobilizing the oligonucleotide onto the surface of a solid-phase substrate by first synthesizing an oligonucleotide having introduced thereonto a reactive group, separately previously surface-treating the surface of the solid-phase substrate so as to render it reactive with the reactive group to form a bond with the oligonucleotide, and spotting the oligonucleotide to form a covalent bond. For example, there has been known a technique of reacting an amino group-introduced oligonucleotide with a slide glass plate having introduced on the surface thereof an amino group via PDC (p-phenylenediisothiocyanate). However, this technique involves the problem that the reaction between PDC and the amino group-introduced oligonucleotide is slow. There has also been a technique of reacting an aldehydo group-introduced oligonucleotide with a slide glass having introduced onto the surface thereof an amino group. However, this technique involves the problem that stability of a reaction product of a Schiff base is so small that there tends to arise hydrolysis.
In recent years, it has also been proposed to use an oligonucleotide analogue, called PNA (peptide nucleic acid), as a probe molecule of a DNA chip in place of an oligonucleotide or polynucleotide (including DNA, DNA fragment, synthesized oligonucleotide or polynucleotide, RNA molecule and RNA fragment). As a measurement chip wherein this PNA is immobilized onto a solid-phase substrate through a covalent bond, it has been proposed to utilize a surface plasmon resonance (SPR) biosensor, use as a solid-phase substrate a transparent substrate having provided thereon a metal film and an organic substance layer comprising a silane coupling agent, immobilize avidin onto the organic substance layer, and immobilize PNA labeled with biotin to avidin (JP-A-11-332595). A DNA fragment bound and immobilized onto the surface of this measurement chip through the probe molecule of PNA by hybridization is detected utilizing the surface plasmon resonance phenomenon.
It has also been known to use a charge-coupled device (CCD) as a substrate of a DNA chip (Nucleic Acids Research, 1994, Vol. 22, No. 11, 2121-2125).
As a protein microarray, a report has been made by Schreiber, et al. which relates to a protein microarray for conducting analysis of mutual action between proteins with a high throughput (Science, 289, 1760-1763, 2000). This is a technique of spotting a protein aqueous solution on a slide glass having aldehydo group and blocking with a BSA solution. The thus-obtained microarray is reacted with a protein solution, followed by detecting using a fluorescence scanner. The microarray obtained by this technique involves the problem that stability of a Schiff base of a reaction product between the aldehydo group the substrate has and the amino group the protein has is so low that its hydrolysis is liable to take place.
In the field of detecting nucleic acids, in the case of using a polyamide film as a solid-phase substrate, immobilization has been conducted by spotting a nucleic acid onto the polyamide film and irradiating with UV rays (BioTechniques 2002, Vol. 33, No. 3, 612-618). This technique involves the problem that it requires a UV apparatus which permits to adjust energy.
Also, there is an example wherein a carboxyl group is introduced onto a polyamide film which is comparatively easily obtainable, and an oligonucleotide is immobilized thereto with a carbodiimide (Nucleic Acids Research, 1991, Vol. 19, No. 14, 3929-3933). However, this technique involves the problem that the polyamide film onto which a carboxyl group has previously been introduced is difficult to obtain.
As a technique for modifying a polyamide film with an isocyanate compound, there has been described a technique of modifying an aromatic polyamide for use as a protective film for glass-made products or as a magnetic tape with a polyisocyanate (JP-A-08-325393).